Earth saw

ABSTRACT

An apparatus used to excavate trenches. In a preferred embodiment the trenching machine has a cutting disc supported on a frame and adapted to operate with the center point of the cutting disc below ground. A spoils handler supported above the cutting disc and forward of the center point is used to move spoils away from the cutting disc. The ratio of cutting depth to weight of the trenching assembly and the cutting depth to wheel diameter is improved through the use of a cutting disc that is concave. The outer rim of the concave disc may support a plurality of replaceable cutting member. The cutting disc is rotated using a drive assembly that is contained within the cutting width of the cutting disc.

FIELD OF THE INVENTION

This invention relates generally to the field of trenching machines andmore specifically to earth saws capable of excavating trenches.

SUMMARY OF THE INVENTION

The present invention is directed to an apparatus for excavatingtrenches. The apparatus comprises a frame, a support assembly connectedto the frame, a trenching assembly and a power supply supported on theframe. The trenching assembly is connected to the support assembly andcomprises a concave cutting disc. The concave cutting disc has an outerrim and at least one cutting member supported by the outer rim. Thepower supply is adapted to drive operation of the trenching assembly.

The present invention is further directed to a trenching assembly forexcavating a trench. The trenching assembly comprises a concave cuttingdisc, a cutting ring, at least one cutting member and a drive assembly.The cutting ring is connected to an outer rim of the concave cuttingdisc and circumscribes the outer rim. The cutting member is supported bythe cutting ring. The drive assembly is disposed within the concavecutting disc and adapted to drive operation of the trenching assembly.

Further still, the present invention is directed to an apparatus forexcavating trenches. The apparatus comprises a frame, a support assemblyconnected to the frame, and a trenching assembly connected to thesupport assembly. The trenching assembly comprises a cutting disc havinga center point, a cutting ring connected to the cutting disc andcircumscribing the cutting disc, and at least one cutting membersupported on the cutting ring. The trenching assembly has a cuttingdepth and a cutting diameter. The trenching assembly is adapted tooperate with the center point of the cutting disc below ground so thatthe ratio of cutting depth to cutting diameter is between 0.5 and 0.8.

The present invention further includes an apparatus for excavating atrench. The apparatus comprises a frame, a cutting disc and a spoilshandler. The cutting disc is supported by the frame and has a centerpoint and a cutting width. The cutting disc is rotatable about thecenter point to excavate the trench with the center point of the cuttingdisc disposed underground during excavation. The spoils handler issupported by the frame and adapted to laterally displace spoils from thecutting disc. The spoils handler is disposed above the cutting disc andforward of the center point and adapted to move spoils laterally andaway from the cutting disc.

The present invention further includes an apparatus for excavating atrench. The apparatus comprises a frame, a support assembly connected tothe frame, and a trenching assembly. The trenching assembly comprises acantilevered drive assembly and a cutting width. The cantilevered driveassembly is contained within the cutting width.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a trenching machine constructed inaccordance with the present invention. The trenching machine of FIG. 1is equipped with a trenching assembly attached to the rear of themachine. The trenching assembly is shown with a cutting disc that isadapted to operate with the center point of the disc below groundsurface.

FIG. 2 is an isometric view of the trenching assembly of FIG. 1. Thetrenching assembly is shown having a concave cutting disc, a cuttingring circumscribing the concave cutting disc, and a drive assembly.

FIG. 3 is a cross-sectional view of the trenching assembly of FIG. 2showing the cutting ring circumscribing the outer rim of the concavecutting disc. FIG. 3 also illustrates the drive assembly supportedwithin the cutting width of the concave cutting disc and driven by amotor.

DESCRIPTION OF THE INVENTION

Turning now to the figures and first to FIG. 1, there is shown thereinan apparatus 10 for excavating trenches, constructed in accordance withthe present invention. The trenching machine 10 comprises a tractor 12.The tractor 12 has a frame 16, having a front end 18, a rear end 20, anda power plant 22 adapted to provide power for various functions of thetrenching machine 10. The tractor 12 further includes an operatorstation 24 supported by the frame 16. The operator station 24 ispositioned on the frame 16 so that the operator has a relativelyunobstructed view of the earth saw attachment 14. The earth sawattachment 14 comprises a support assembly 26 that connects thetrenching assembly 27 to the frame 16. The power plant 22 may bepositioned at the front end 18 of the frame 16 to counter-balance theearth saw attachment 14.

The frame 16 is adapted to support a drive system 28 for propelling thetrenching machine 10 in a plurality of directions. The drive system 28shown in FIG. 1 comprises pneumatic tires 30 with conventional frontwheel steering. The drive system 28 may be controlled in a conventionalmanner using the combination of a steering wheel 32 and foot pedals 34and hand controls 36. However, it will be appreciated that the drivesystem 28 may comprise an all-terrain endless track system and iscapable of being steered in a skid, articulated or coordinatedarrangement without departing from the spirit of the invention.

As previously discussed, the power plant 22 is supported near the frontend 18 of the frame 16. The power plant 22 may comprise an internalcombustion engine supported within an engine compartment 38. It will beappreciated, of course, that different types of engines or power sourcesmay be used to power the trenching machine 10. The power plant 22provides power to drive operation of the drive system 28 and thetrenching assembly 27. The engine compartment 38 of the power plant 22is sloped such that an operator positioned at the operator station 24has a relatively unobstructed line-of-sight to the ground surface infront of the tractor 12.

Continuing with FIG. 1, a work member 40 may be supported at the frontend 18 of the frame 16. The work member 40 may comprise a tool carrier42 adapted to support a wide variety of work tools at the front end 18of the frame 16. For illustrative purposes, the work tool shown attachedto the tool carrier 42 in FIG. 1 is a backfill blade 44 that may be usedto push excavated soil back into an open trench. The backfill blade 44may be articulated (angled and tilted) to a number of varying angles oforientation using hydraulic cylinders (not shown). The tool carrier 42and backfill blade 44 are supported by one or more lift arms 46 that arepivotally connected to the frame 16 at pivot point 48. The lift arms 46are movable in a range of motion comprising a lower position and anupper position (shown in FIG. 1). The lift arms 46 may be raised andsupported at any position within their range of motion using one or morehydraulic cylinders 50.

As previously discussed, the operator station 24 is supported by theframe 16 and may comprise the steering wheel 32, pedals 34, and variousdifferent work member 40 and earth saw attachment 14 controls 36. Theoperator station 24 may further comprise an operator seat 52 that has avertical pivot axis 56 to allow the operator to turn and view the earthsaw attachment 14 when in operation. The operator station 24 may furthercomprise a roll-over protective structure (“ROPS”) 58 supported by theframe 16. The ROPS 58 preferably has front 60 and rear 62 vertical postsand a canopy 64 supported by the vertical posts. It will be appreciatedthat alternative ROPS configurations may be used by one skilled in theart without departing from the spirit of the invention.

The earth saw attachment 14 comprises the support assembly 26, thetrenching assembly 27 and a saw frame 89. The support assembly 26attaches the trenching assembly 27 to the frame 16. The support assembly26 supports the trenching assembly 27 so that it is movable about both afirst axis 72 and a second 74 axis, both of which are orthogonal to acentral longitudinal axis (not shown) of the frame 16. A first actuator76 and a second actuator 78 are adapted to move the trenching assembly27 about the first 72 and second axis 74, respectively.

The support assembly 26 may be cantilevered and comprises a removableattachment means 66, a tool carrier 80, a mounting bracket 82connectable with the tool carrier and a swing post 84. The removableattachment means 66 forms part of the frame 16 and is adapted to supporta wide variety of work attachments. The tool carrier 80 is connected tothe removable attachment means 66 and may comprise a top rail 86 and abottom rail 88 both of which extend across the width of the rear end 20of the frame 16. The mounting bracket 82 is adapted to hang from andslide along the top 86 and bottom rails 88 of the tool carrier 80 sothat the trenching assembly 27 may be traversed along the width of thetractor 12. Hydraulic cylinders (not shown) may be used to push and pullthe mounting bracket 82 and the trenching assembly 27 along the toolcarrier rails 86, 88. However, the saw can be mounted to the tractor inother configurations including 1) with the traversing frames 80 and 82but without the swing post 84, 2) without the traversing frame but withthe swing post and 3) without the traversing frame and without the swingpost.

The swing post 84 and first actuator 76 form a cantilevered supportassembly which allows the trenching assembly 27 to be pivoted about thefirst pivot axis 72. The first pivot axis 72 is orthogonal to thecentral longitudinal axis of the frame 16. The swing post 84 ispivotally connected to the mounting bracket 82 and defines the firstaxis 72. The first actuator 76 may comprise a hydraulic cylinderconnected to the mounting bracket 82 at one end and the swing post 84 atthe other end.

Continuing with FIG. 1, the swing post 84 supports a saw frame 89 at therear 16 of the trenching machine 10. The saw frame 89 supports thetrenching assembly 27 and covers the above ground portion of theassembly. The saw frame 89 may be connected to the swing post 84 usingpins positioned through a mounting hole 92 in the swing post. Theconnection between the saw frame 89 and the swing post 84 defines asecond pivot axis 74 about which the trenching assembly 27 may be raisedand lowered. The second actuator 78 is connected to the swing post 84and the saw frame 89. The second actuator 78 is adapted to raise andlower the trenching assembly 27. As shown in FIG. 1, when the secondactuator 78 comprising a hydraulic cylinder is retracted the trenchingassembly 27 is pivoted downward. The hydraulic cylinder 78 may bepressurized to extend the cylinder to any one of a plurality of lengthsto vary the cutting depth 94 of the trenching assembly 27. Additionally,when the second actuator 78 is fully extended the trenching assembly 27may be pivoted upward to a stowed position so that it does not contactthe ground. When the saw is in the lowered position, floating shoe 91rides on the ground surface closing the variable space between the sawframe 89 and the ground surface. Additionally, trench cleaner 93 islowered into the cut trench with a hydraulic cylinder (not shown) tofollow behind the cutting wheel for scraping cuttings forward into thewheel to provide a resultant trench with minimal residual cuttings.

The saw frame 89 is adapted to support trenching assembly 27. Powersupply 96 is attached to drive assembly 102 to drive operation of thetrenching assembly 27 and may comprise a hydraulic motor.

The trenching assembly 27 may comprise a concave cutting disc 98,cutting members 100 and a drive assembly 102. The concave cutting disc98, cutting ring 124 and cutting members 100 comprise the cutting depth94. The cutting depth 94 corresponds to the maximum depth at which thetrenching assembly 27 is operable to excavate the desired trench. Thecutting depth 94 of the embodiment shown in FIG. 1 is preferably betweentwenty (20) and forty (40) inches, and more preferably at least thirty(30) inches. Further, the trenching assembly 27 comprises a cuttingdiameter 103 that is related to the diameter of the concave cutting disc98, cutting ring 124 and cutting members 100. The cutting diameter 103of the trenching assembly 27 of FIG. 1 is preferably between thirty-six(36) inches and fifty-six (56) inches and more preferably forty-six (46)inches. Thus, the construction of the trenching assembly 27 as describedherein and illustrated in FIG. 1 provides a ratio of cutting depth 94 tocutting diameter 103 that is preferably between 0.5 and 0.8, and morepreferably 0.65.

A spoils handler 104 is supported by the saw frame 89 so that it isdisposed proximate and tangentially in line to the concave cutting disc98. The spoils handler 104 may comprise an impeller 105 positioned abovethe concave cutting disc 98 and forward of its center point 106. Theblades of the impeller 105 are contoured in a concave manner tocorrespond to the arcuate path of the cutting members 100. It will beappreciated that the spoils handler 104 may be configured so that it iscontained within the lateral width of the saw frame 89. Operation of theimpeller 105 may be driven by a hydraulic motor (not shown) capable ofselectively rotating the impeller either clockwise or counter-clockwise.Rotation of the impeller causes discharge of the spoils carried upwardby the concave cutting disc 98 perpendicular to the concave cutting disc98 through a discharge opening 112 in the saw frame 89. The largestradial diameter tips of the blades of the impeller 105 protrude throughthe side plates of saw frame 89 and into the discharge opening 112. Itwill be appreciated that a second discharge opening (not shown) may beprovided on the opposing plate of the saw frame 89. Additionally, acover (not shown) may be placed over the discharge opening 112 tofacilitate discharge of spoils to the desired side of the trenchingassembly 27 through the selected discharge opening.

Turning now to FIG. 2, there is shown therein an isometric view of thetrenching assembly 27 of the present invention showing the relationshipof the concave cutting disc 98 to the drive assembly 102. FIG. 2illustrates that the drive assembly 102 is disposed within the concavecutting disc 98 and may be driven by the power supply 96. As shown inFIG. 2, the power supply 96 may be bolted to a drive assembly cover 116and positioned to drive rotation of the concave cutting disc 98. Thedrive assembly cover 116 is constructed to support bolts 121 that areused to connect the trenching assembly 27 to the saw frame 89 in acantilevered manner.

The concave cutting disc 98 may be constructed from a single hardenedsteel plate that has been pressed to form an outer rim 122. A cuttingring 124 is connected to the concave cutting disc 98 so that itcircumscribes the outer rim 122. The cutting ring 124 is also preferablyconstructed from hardened steel and may be welded to the outer rim 122.Welding of the cutting ring 124 with cutting members 100 to the outerrim 122 allows the drive assembly 102 to be positioned in closeproximity to the outer rim of the concave cutting disc 98 to maximizecutting depth 94 for a given disc diameter. The cutting ring 124supports a plurality of cutting members 100 that are circumferentiallyspaced about the periphery of the cutting ring 124. The cutting members100 may comprise sockets 126 that are welded to the cutting ring 124.The sockets 126 may comprise an aperture 127 adapted to receive acorrespondingly shanked bit 128.

Sockets 126 with correspondingly insertable bits 128 allow forreplacement of worn or broken cutting members. The bit 128 may comprisea shanked body (not shown) that corresponds to the aperture 127 of thesocket 126 and a cutting member 100 having a cutting element 130. Thebody of the bit 128 is generally constructed from a hardened alloy suchas steel while the cutting element 130 is made with a carbide insert orcap. The cutting member 100 comprising the socket 126 and bit 128defines a plane 132 that may be centered or uncentered relative to thedirection of rotation of the cutting disc 98 and defines the cuttingwidth 108.

The construction of the earth saw attachment 14 permits the trenchingassembly 27 to operate at greater depths than previously attained byearth saws and tractors 12 of same or similar size and weight.Containment of the drive assembly 102 within the cutting width 108 (FIG.3) of the trenching assembly 27 permits the trenching assembly tooperate with the center point 106 of the concave cutting disc 98 belowground surface. The cutting width 108 of the present embodiment iscomprised of the cutting disc 98 and the cutting members 100 and ispreferably between 4.75 inches and 7 inches for an earth saw attachment14 adapted to reach cutting depths 94 of between twenty (20) to forty(40) inches, and more preferably a depth of thirty (30) inches. Thus,the trenching assembly 27 of the present invention may have a cuttingwidth 108 to cutting depth 94 ratio between 0.24 and 0.12, with apreferred ratio of 0.16.

The single plate concave cutting disc 98, cutting ring 124 and driveassembly 102 significantly reduce the overall weight of the earth sawattachment 14 related to the cutting depth 94. For example, the earthsaw attachment 14 comprised of the support assembly 26, the trenchingassembly 27 and saw frame 89 may preferably have a gross attachmentweight of between 1400 pounds and 3000 pounds, and more preferably aweight of 2200 pounds. The cutting depth 94 of the trenching assembly 27in FIG. 1 is preferably between twenty (20) inches and forty (40)inches. Thus, the ratio of cutting depth 94 of the trenching assembly 27shown in FIGS. 1 and 2 to attachment weight may preferably be between0.01 and 0.02 inches per pound with a preferred ratio of 0.014 inchesper pound. The reduced attachment weight of the earth saw attachment 14reduces the amount of counterweights 134 (FIG. 1) and makes the tractor12 lighter and more maneuverable. Additionally, it will be appreciatedthat the ability to operate with the center point 106 below the surfacepermits the use of a disc having a smaller diameter than traditionallyrequired to reach the same cutting depth and further reduces the grossweight of the earth saw attachment 14.

Turning now to FIG. 3 there is shown therein a cross-sectional view ofthe trenching assembly 27. As previously discussed, the trenchingassembly 27 comprises the drive assembly 102, concave cutting disc 98,cutting ring 124 and cutting members 100. The drive assembly 102 isoperable in response to movement of a rotatable drive shaft 118 drivenby the power supply 96. The drive assembly 102 comprises the first gear120, the second gear 136 and a rotatable hub 138. The first gear 120 maybe splined for mating connection with a splined drive shaft 118. Thesecond gear 136 is operably connected to the hub 138. The first gear120, second gear 136, hub 138 and concave cutting disc 98 are adapted torotate in response to rotation of the drive shaft 118. A torque transferdevice such as a chain (not shown) may be used to transfer therotational energy generated by the power supply 96 to the second gear136 and concave cutting disc 98. In a preferred embodiment, the firstgear 120 may comprise eleven teeth and the second gear 136 may comprisethirty-two teeth. The relative size of the first gear 120 to the secondgear 136 allows for the use of a hydraulic motor 96 that is adapted torotate the drive shaft 118 at a higher speed and of less weight thanmotors typically used in similar applications.

The second gear 136 is supported on the drive assembly 102 by arotatable hub 138. The rotatable hub 138 is bearingly mounted to thedrive assembly cover 116. The second gear 136 is welded to the rotatablehub 138. However, it will be appreciated that the hub 138 and secondgear 136 may be integrally formed or assembled such as with a splined orbolted connection. The concave cutting disc 98 is connected to the hub138 using bolts 140 so that the concave cutting disc is rotated with thesecond gear 136 and hub. The concave cutting disc 98 and hub 138 may besupported in a cantilevered manner by the drive assembly cover 116. Acover plate 142 on the concave cutting disc 98 reduces the intrusion ofspoils into the drive assembly 102 and substantially protects the bolts140 from wear. Bolting the concave cutting disc 98 to the hub 138permits removal of the concave cutting disc without disturbing theintegrity of the drive assembly 102. Thus, alternative cutting discshaving a different cut width can be installed on to the earth sawattachment 14.

Various modifications can be made in the design and operation of thepresent invention without departing from the spirit thereof. Thus, whilethe principal preferred construction and modes of operation of theinvention have been explained in what is now considered to represent itsbest embodiments, which have been illustrated and described, it shouldbe understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically illustratedand described.

1. An apparatus for excavating trenches comprising: a work machine; aframe connected to the work machine; a trenching assembly connected tothe frame, the trenching assembly comprising: a cutter disc comprising acentral planar portion terminating peripherally in a rim extendinggenerally perpendicular to the central planar portion, wherein the rimcomprises an outer surface; a ring connected to the outer surface of therim and circumscribing the cutter disc; and at least one cutting membersupported on the ring; and a power supply supported by the frame andadapted to drive operation of the trenching assembly; a drive assemblydisposed within the central planar portion and adapted to both supportthe cutter disc and transmit rotational energy from a power supply tothe cutter disc to drive rotation of the cutter disc from only one sideof the cutter disc.
 2. The apparatus of claim 1 wherein the ringcomprises one or more segments connected to the outer surface of thecutter disc.
 3. The apparatus of claim 1 wherein the frame is furtheradapted to cover an above-ground portion of the trenching assembly, theapparatus further comprising a spoils handler supported within the frameand adapted to move spoils laterally away from the trenching assemblythrough an opening in the frame immediately above the cutter disc. 4.The apparatus of claim 1 further comprising a spoils handler connectedto the frame and adapted to move spoils in a lateral direction away fromthe trenching assembly.
 5. (canceled)
 6. The apparatus of claim 5wherein the power supply comprises a rotatable drive shaft and whereinthe drive assembly comprises: a first gear operably connected to thedrive shaft for rotation therewith; and a second gear connected to thecutter disc and adapted to rotate in response to rotation of the firstgear and drive shaft.
 7. (canceled)
 8. (canceled)
 9. A trenchingassembly for excavating a trench comprising: a cutter disc comprising acentral planar portion terminating peripherally in a rim extendinggenerally perpendicular to the central planar portion, wherein the rimcomprises an outer surface, and wherein the rim and central planarportion delimit an internal space; a ring connected to the outer surfaceand circumscribing the cutter disc; at least one cutting memberconnected to the ring; and a drive assembly disposed within the internalspace and adapted to both support the cutter disc and transmitrotational energy from a power supply to the cutter disc to driverotation of the cutter disc from only one side of the cutter disc. 10.The trenching assembly of claim 9 wherein the power supply comprises ahydrostatic motor.
 11. The trenching assembly of claim 10 wherein thedrive assembly comprises: a first gear connectable to the power supply;and a second gear supported within the internal space and adapted torotate in response to rotation of the first gear.
 12. The trenchingassembly of claim 9 comprising a cutting depth and a cutting diameter,wherein the ratio of the cutting depth to the cutting diameter isbetween 0.5 and 0.8.
 13. (canceled)
 14. The trenching assembly of claim9 wherein the cutter disc comprises a center point and wherein thecutter disc is adapted to operate with the center point of the cutterdisc below ground.
 15. An apparatus for excavating trenches comprising:a frame; a support assembly connected to the frame; a trenching assemblyconnected to the support assembly, wherein the trenching assemblycomprises a cutter disc comprising a central planar portion terminatingperipherally in a rim extending generally perpendicular to the centralplanar portion, and an internal space delimited by the rim and thecentral planar portion; a drive assembly for mounting the trenchingassembly to the support assembly disposed within the internal space andadapted to support the cutter disc from only one side of the cutter discand to transmit rotational energy from a power supply to the cutter discto drive rotation of the cutter disc from only one side of the cutterdisc.
 16. The apparatus of claim 15 wherein the cutting depth of thetrenching assembly is between twenty and forty inches.
 17. The apparatusof claim 16 wherein the cutting width of the trenching assembly isbetween 4.75 and 7 inches.
 18. The apparatus of claim 15 wherein theratio of cutting depth of the trenching assembly to cutting diameter ofthe trenching assembly is 0.65.
 19. (canceled)
 20. The apparatus ofclaim 15 further comprising a spoils handler connected to the frame anddisposed proximate to the trenching assembly.
 21. The apparatus of claim20 wherein the spoils handler is disposed immediately above thetrenching assembly.
 22. (canceled)
 23. (canceled)
 24. (canceled)
 25. Theapparatus of claim 15 wherein the cutting depth and the cutting diametercomprise a ratio of between 0.5 and 0.8.
 26. (canceled)
 27. Theapparatus of claim 15 wherein the trenching assembly has a cutting widthof between 4.75 and 7 inches and wherein the cutting depth of thetrenching assembly is between twenty and forty inches.
 28. The apparatusof claim 15 wherein the ratio of the cutting width to the cutting depthis approximately 0.16.
 29. An apparatus for excavating a trenchcomprising: a frame comprising a hood; a trenching assembly supported bythe frame, the trenching assembly comprising: a cutter disc, the cutterdisc comprising a central planar portion terminating peripherally in arim extending generally perpendicular to the central planar portionwherein the rim comprises an outer surface a ring connected to the outersurface and circumscribing the cutter disc, wherein the ring is adaptedto support a plurality of cutting members; wherein the hood of the frameis adapted to cover an above-ground portion of the cutter disc; whereinthe cutter disc is rotatable to excavate the trench; a spoils handlersupported inside the hood immediately above the cutter disc and adaptedto laterally displace spoils from immediately above the cutter disc anda drive assembly disposed within the central planar portion and adaptedto both support the cutter disc and transmit rotational energy from apower supply to the cutter disc to drive rotation of the cutter discfrom only one side of the cutter disc.
 30. (canceled)
 31. (canceled) 32.The apparatus of claim 29 further comprising a power supply having adrive shaft adapted to drive rotation of the cutter disc, and whereinthe drive assembly comprises: a first gear operably connected to thedrive shaft for movement therewith; and a second gear connected to a oneside of the cutter disc and adapted to move in response to movement ofthe drive shaft and the first gear.
 33. The apparatus of claim 29wherein the trenching assembly comprises a cutting depth and a cuttingdiameter and wherein the ratio of the cutting depth to the cuttingdiameter is between 0.5 and 0.8.
 34. An apparatus for excavating atrench comprising: a frame; a support assembly connected to the frame; atrenching assembly, the trenching assembly comprising a cutter disccomprising: a central planar portion terminating peripherally in a rimextending generally perpendicular to the central planar portion, theperipheral rim having an outer surface; and an internal space delimitedby the peripheral rim and central planar portion; a drive assembly formounting the trenching assembly to the support assembly disposed withinthe internal space and adapted to support the cutter disc from only oneside of the cutter disc and to transmit rotational energy from a powersupply to the cutter disc to drive rotation of the cutter disc from onlyone side of the cutter disc.
 35. The apparatus of claim 34 wherein thetrenching assembly further comprises a ring connected to the outersurface of the rim and circumscribing the rim, and wherein a pluralityof cutting members are connected to the ring so that each connectionbetween the ring and the plurality of cutting members is disposed beyondthe rim of the cutter disc.
 36. The apparatus of claim 35 wherein thecutter disc comprises a cutting width of at least 4.75 inches.
 37. Theapparatus of claim 35 wherein the cutter disc comprises a cutting depthof at least thirty inches.
 38. The apparatus of claim 34 wherein thecutting width of the trenching assembly is between 4.75 and 7 inches andwherein the trenching assembly comprises a cutting depth of betweentwenty and forty inches.
 39. The apparatus of claim 34 wherein the ratioof the cutting width to the cutting depth is approximately 0.16.
 40. Theapparatus of claim 34 wherein the ratio of cutting depth to cuttingdiameter is approximately 0.65.
 41. (canceled)
 42. (canceled)